Abstract

Dried Chrysanthemum morifolium flowers have traditionally been used in Korea for the treatment
of insomnia. This study was performed to investigate whether the ethanol extract of Chrysanthemum
morifolium flowers (EFC) enhances pentobarbital-induced sleep behaviors. EFC prolonged sleep time
induced by pentobarbital similar to muscimol, a GABAA receptors agonist. EFC also increased sleep
rate and sleep time when administrated with pentobarbital at a subhypnotic dosage. Both EFC and
pentobarbital increased chloride (Cl−) influx in primary cultured cerebellar granule cells. EFC
increased glutamic acid decarboxylase (GAD) expression levels, but had no effect on the expression
of α1-, β2-, and γ2-subunits of the GABAA receptor in the hippocampus of a mouse brain. This is in
contrast to treatment with pentobarbital, which showed decreased α1-subunit expression and no
change in GAD expression. In conclusion, EFC augments pentobarbital-induced sleep behaviors;
these effects may result from Cl− channel activation.